Commonly, halogenated waste materials are disposed of via burning at high temperatures. The halogenated waste materials are initially combusted at high temperature conditions to form halogen containing flue gas. The halogen in the resulting flue gas is then generally recovered in the form of acid. By recovering the halogen, the cost involved in disposing the waste materials and in providing halogen materials to halogen utilizing processes can be substantially reduced.
It has been known to use air burners to incinerate halogenated waste materials. This technique, however, is inefficient for a number of reasons. First, a high incineration temperature, i.e. above 1,300.degree. C., is difficult to obtain unless a substantial amount of additional rich fuel is provided. The use of a substantial amount of additional rich fuel, however, may not be feasible due to the cost involved. Second a short residence time is obtained due to the formation of a large volume of combustion gases (flue gas). The residence time is a function of the sizes of incineration equipment and the volume of combustion gases formed. When the volume of combustion gases is increased in a given incineration system, the residence time is correspondingly decreased. The failure to obtain a long residence time may adversely affect the incineration of halogenated waste materials. It should be noted the both the longer residence time and high incineration temperature are desirable not only to increase the rate at which halogenated waste materials are incinerated but also to insure the complete destruction of the halogenated waste materials.
It has been, therefore, proposed in U.S. Pat. No. 4,233,280 and in an article on "BASF Process" by Stauffer Chemical Company that oxygen, instead of air, be employed to incinerate halogenated waste at a pressure of about 7.5 barg. The use of oxygen at this pressure provides a temperature as high as 2,500.degree. C. and reduces the amount of a flue gas formed due to the absence of nitrogen. As a result of a high temperature and of a decreased volume of the flue gas, the residence time of the flue gas in a postcombustion zone, i.e. a reaction zone, is advantageously increased. The combined effect of higher pressure, high temperature and increased residence time leads to a higher conversion of the halogen in the flue gas into the corresponding acid. The use of oxygen, however, requires means by which high temperature conditions and flame sizes can be controlled such that damage to the refractory wall of the incinerator is prevented. Building an external cooling jacket around the combustion and postcombustion zones of the incinerator is taught by U.S. Pat. No 4,233,280 and the above Stauffer Chemical company article. The use of the external cooling jacket, however, is constrained by the availability of heat exchange surface areas and the heat conductivity of refractory walls around the combustion zone of an incinerator. The difficulty of utilizing the jacket to avoid the risk of damage to the refractory wall of an incinerator is especially evident when a Particular area subject to high heat needs to be cooled in a localized or concentrated fashion.
To correct these shortcomings, the flame resulting from combustion of chlorinated waste materials in the presence of oxygen may be directly cooled with water. By spraying water towards the flame, the temperature and the length of the flame in an incinerator could be regulated and controlled. A desired temperature could, for example, be obtained at the top of the combustion zone while preventing the risk of damage to the refractory wall. This desired temperature, however, may not be maintained throughout the incinerator or throughout the combustion zone of the incinerator. In fact, the temperature decreases sharply from the top of the combustion zone to a downstream postcombustion zone, i.e. a reaction zone, thereby limiting the conversion of the halogen into acid and the corresponding incineration throughput.
As used herein the term "the incineration throughput" means a rate at which the waste is incinerated.